We have characterized CReMM, a new member of the CHD family of chromatin remodeling proteins. CReMM is rearranged in a large fraction of osteosarcomas, implicating the disruption of this new protein in an important human disease. This protein was isolated by immunocloning from marrow stromal cells, and contains motifs for interaction with steroid receptors. The protein contains two chromodomains, a SNF2/helicase remodeling domain, a SANT domain, and an A/T hook DNA binding domain. Unexpectedly, the protein interacts with both Pol II and Pol I promoters, and is localized either to the nucleoplasm or to the nucleolar fibrillar transcription centers (FTC) in a phosphorylation dependent manner. These findings suggest CReMM is a new chromatin remodeling factor that is involved in both Pol II and Pol I transcription. Molecular clones of the CReMM protein have been characterized. A large fragment representing 85% of the protein has been expressed in baculovirus and purified from infected cells. This protein has been shown to have DNA dependent ATPase activity, and to carry out nucleosome remodeling by two separate assays, nucleosome sliding, and nuclease resolved nucleosome reorganzation. Thus, the CReMM protein is a functional member of the CHD remodeling family.